<!DOCTYPE html>
<html lang="zh-CN">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>404 - 页面未找到</title>
    <style>
        * {
            margin: 0;
            padding: 0;
            box-sizing: border-box;
        }

        body {
            font-family: 'Microsoft YaHei', Arial, sans-serif;
            background: linear-gradient(135deg, #0f2027, #203a43, #2c5364);
            min-height: 100vh;
            display: flex;
            justify-content: center;
            align-items: center;
            overflow: hidden;
            position: relative;
        }

        body::before {
            content: '';
            position: absolute;
            top: 0;
            left: 0;
            width: 100%;
            height: 100%;
            background: 
                radial-gradient(circle at 20% 30%, rgba(255,255,255,0.1) 0%, transparent 40%),
                radial-gradient(circle at 80% 70%, rgba(255,255,255,0.1) 0%, transparent 40%);
            z-index: -1;
        }

        .container {
            text-align: center;
            padding: 40px;
            background: rgba(255, 255, 255, 0.08);
            border-radius: 20px;
            border: 1px solid rgba(255, 255, 255, 0.2);
            box-shadow: 0 15px 35px rgba(0, 0, 0, 0.5);
            max-width: 500px;
            width: 90%;
            backdrop-filter: blur(12px);
            position: relative;
            overflow: hidden;
        }

        .container::before {
            content: '';
            position: absolute;
            top: -50%;
            left: -50%;
            width: 200%;
            height: 200%;
            background: linear-gradient(45deg, transparent, rgba(255,255,255,0.1), transparent);
            transform: rotate(30deg);
            z-index: -1;
        }

        .error-code {
            font-size: 120px;
            font-weight: 700;
            color: #fff;
            margin-bottom: 10px;
            text-shadow: 0 0 20px rgba(0, 200, 255, 0.5);
            animation: pulse 2s infinite;
        }

        @keyframes pulse {
            0% { text-shadow: 0 0 20px rgba(0, 200, 255, 0.5); }
            50% { text-shadow: 0 0 30px rgba(0, 200, 255, 0.8); }
            100% { text-shadow: 0 0 20px rgba(0, 200, 255, 0.5); }
        }

        .error-title {
            font-size: 28px;
            color: #fff;
            margin-bottom: 15px;
            font-weight: 600;
        }

        .error-message {
            color: #a0d2ff;
            font-size: 16px;
            margin-bottom: 30px;
            line-height: 1.6;
        }

        .illustration {
            margin: 30px 0;
            position: relative;
        }

        .planet {
            width: 80px;
            height: 80px;
            background: linear-gradient(135deg, #00c9ff 0%, #0066ff 100%);
            border-radius: 50%;
            margin: 0 auto 20px;
            position: relative;
            animation: float 3s ease-in-out infinite;
            box-shadow: 0 0 20px rgba(0, 201, 255, 0.5);
        }

        .planet::before {
            content: '';
            position: absolute;
            top: 10px;
            left: 10px;
            width: 20px;
            height: 20px;
            background: rgba(255, 255, 255, 0.3);
            border-radius: 50%;
        }

        @keyframes float {
            0%, 100% { transform: translateY(0); }
            50% { transform: translateY(-10px); }
        }

        .stars {
            position: absolute;
            width: 100%;
            height: 100%;
            top: 0;
            left: 0;
        }

        .star {
            position: absolute;
            width: 2px;
            height: 2px;
            background: white;
            border-radius: 50%;
            animation: twinkle 3s infinite;
        }

        @keyframes twinkle {
            0%, 100% { opacity: 0; }
            50% { opacity: 1; }
        }

        .action-buttons {
            display: flex;
            gap: 15px;
            justify-content: center;
            flex-wrap: wrap;
            margin-top: 30px;
        }

        .btn {
            padding: 12px 24px;
            border: none;
            border-radius: 8px;
            font-size: 14px;
            font-weight: 600;
            cursor: pointer;
            transition: all 0.3s ease;
            text-decoration: none;
            display: inline-block;
            position: relative;
            overflow: hidden;
            z-index: 1;
        }

        .btn::before {
            content: '';
            position: absolute;
            top: 0;
            left: 0;
            width: 100%;
            height: 100%;
            background: linear-gradient(135deg, #00a3ff 0%, #0055cc 100%);
            opacity: 0;
            transition: opacity 0.3s ease;
            z-index: -1;
        }

        .btn-primary {
            background: linear-gradient(135deg, #00c9ff 0%, #0066ff 100%);
            color: white;
        }

        .btn-primary:hover {
            transform: translateY(-2px);
            box-shadow: 0 5px 20px rgba(0, 201, 255, 0.5);
        }

        .btn-primary:hover::before {
            opacity: 1;
        }

        .btn-secondary {
            background: rgba(255, 255, 255, 0.1);
            color: white;
            border: 1px solid rgba(255, 255, 255, 0.2);
        }

        .btn-secondary:hover {
            background: rgba(255, 255, 255, 0.2);
            transform: translateY(-2px);
            box-shadow: 0 5px 15px rgba(255, 255, 255, 0.1);
        }

        .btn-secondary:hover::before {
            opacity: 1;
        }

        .footer {
            margin-top: 30px;
            padding-top: 20px;
            border-top: 1px solid rgba(255, 255, 255, 0.1);
        }

        .footer p {
            color: #a0d2ff;
            font-size: 12px;
        }

        .footer a {
            color: #00c9ff;
            text-decoration: none;
            transition: all 0.3s ease;
            position: relative;
        }

        .footer a:hover {
            color: #00a3ff;
        }

        .footer a::after {
            content: '';
            position: absolute;
            bottom: -2px;
            left: 0;
            width: 0;
            height: 1px;
            background: #00c9ff;
            transition: width 0.3s ease;
        }

        .footer a:hover::after {
            width: 100%;
        }

        @media (max-width: 480px) {
            .error-code {
                font-size: 80px;
            }
            
            .error-title {
                font-size: 24px;
            }
            
            .error-message {
                font-size: 14px;
            }
            
            .planet {
                width: 60px;
                height: 60px;
            }
        }
    </style>
</head>
<body>
    <div class="container">
        <div class="stars" id="stars"></div>
        
        <div class="error-code">404</div>
        <h1 class="error-title">页面未找到</h1>
        <p class="error-message">
            抱歉，您访问的页面不存在或已被移除。<br>
            请检查网址是否正确，或返回上一页继续浏览。
        </p>
        
        <div class="illustration">
            <div class="planet"></div>
            <div class="stars" id="planetStars"></div>
        </div>
        
        <div class="action-buttons">
            <a href="index.html" class="btn btn-primary">返回首页</a>
            <a href="Login.html" class="btn btn-secondary">登录</a>
            <a href="Register.html" class="btn btn-secondary">注册</a>
            <a href="javascript:history.back()" class="btn btn-secondary">返回上一页</a>
        </div>
        
        <div class="footer